One known form of rotary roof vent comprises a cylindrical-shaped rotary component and a roof base component that anchors the vent above an opening on the roof of a building. The rotary component includes a series of vertically oriented blades between circular top and bottom bases. The rotary component has a relatively flat profile so that the vent projects only a minimal distance above the roof. Wind force on the blades causes the rotary component to rotate, in order to enhance airflow through the vent to thereby assist ventilation of the building and improve rain protection.
The rotary component is generally orientated in a horizontal configuration and an adjustable or custom made roof base is needed for a sloping or pitched roof to maintain the horizontal aspect of the rotary component.